1. Field of the Invention
The present invention relates to air conditioning systems, and more particularly, to an improved air conditioning system, in which fresh air prepared separately can be supplied to a room.
2. Background of the Related Art
The air conditioner is an appliance for cooling or heating a room by using a property of refrigerant in which the refrigerant discharges or absorbs heat to/from an environment when the refrigerant undergoes a phase change.
In general, the air conditioner is provided with an indoor unit and an outdoor unit, wherein the air conditioner having the indoor unit and the outdoor unit combined into one unit is called as a unit type air conditioner, and the air conditioner having the indoor unit and the outdoor unit fabricated individually is called as a separate type air conditioner.
As a typical example of the unit type air conditioner, there is a window type air conditioner, and as the separate type air conditioners, there are a ceiling type air conditioner, a wall mounting type air conditioner, and a package type air conditioner. In a case of the ceiling type air conditioner, the indoor unit is installed in the ceiling, in a case of the wall mounting type, the indoor unit is mounted on a wall, and in a case of the package type air conditioner, the indoor unit stands on a floor in a room.
In general, the air conditioner includes a compressor, a condenser, an expansion device, and an evaporator. The compressor compresses low temperature/low pressure gas refrigerant to high temperature/high pressure refrigerant, and makes the refrigerant to pass through different units. The condenser condenses the gas refrigerant from the compressor into a liquid refrigerant. In this instance, as the refrigerant discharges heat when the refrigerant is condensed, the condenser discharges heat to an environment. As the heat is discharged from the condenser to the room, the room can be heated.
In general, as the expansion device, expanding the condensed refrigerant by decompression, capillary tubes are used. The evaporator vaporizes the expanded refrigerant, when the refrigerant absorbs heat to cool down air around the evaporator. When such a cooled down air is discharged to the room, the room can be cooled down.
In the meantime, for reducing heat loss during use of the air conditioner, the room is closed. Air in such a closed room is polluted gradually as time passes by. For an example, breathing of persons in the room makes a carbon dioxide content in the room air higher, and there is much dust circulating in the dry air. Therefore, after using the air conditioner for a time period, it is required to supply external air fresh relative to the room air into the room.
There are two ways of ventilation. One is forced discharge of an inside air by using a ventilating device, and the other is opening door or window for natural ventilation. Both methods supply external air to the room. However, if the outdoor air is heavily polluted by environmental pollution or sandy dust phenomena, the ventilation of the room with the outdoor air can pollute the room air, on the contrary.
In the ventilation, cold or hot air is discharged to an outside of the room directly, and external air is introduced into the room through an opened door or window, directly. Accordingly, there is a great loss of heat in the ventilation, to require, not only much energy, but also a long time to cool or heat the room again.
In the meantime, if the air conditioning system is provided with a ventilation device, the air conditioning system requires a great number of ducts, to make installation complicate and difficult.